Fiber to the home (FTTH) access communications systems use optical triplexer filters which typically include an upstream 1310 nm laser with a power monitor, a downstream 1490 nm digital receiver, and a downstream 1555 nm video receiver. This triplexer filter must exhibit low loss and provide high wavelength isolation. It must also be physically small and very low cost for access system applications.
Current FTTH systems use commercially available bulk optics filters, which provide low cost, high optical isolation and small form factor. However, they requires hermetically sealed packaging and externally co-packaged APD and PIN detectors. Other technologies include planar lightwave circuits (PLC) using standard silica waveguide having a low-contrast waveguide design which increases the chip area (leading to lower wafer yield and higher cost) and requires photodiodes (PIN and APD) to be hybrid attached to the die. This attachment increases the overall size of the component and its cost.